I usually get a yard for making the DKs. I can get about 6 out of one yard usually. Yes it does make a difference if the repeats are wider or closer together.
I usually find 5 repeats in a quarter yard so I suppose for one DK you would need a half yard. You have to be careful because some repeats can be on the edge and get cut off. so count all 10 of the repeats before you buy the fabric.
I'm making hotpads right now with them. I have started buying an extra yard so I can use the same fabric for the backing. I like to show the fabric the DK came from.